1. Field of the Invention
The present invention relates to a digital single lens reflex camera, and in particular, relates to an arrangement of an image pickup device, a rigid substrate and a finder optical system therein.
2. Description of the Related Art
In a known digital single lens reflex camera which has a reflector in a photographic light path to reflect object-carrying light transmitted through a photographic optical system toward a finder optical system, an image pickup device is provided at the imaging plane of the photographic optical system.
The reflector placed in the photographic light path can be, for example, a quick return mirror, a quick return half mirror, or a stationary half mirror (beam splitter or semitransparent element). One of the most significant differences between a digital still single lens reflex camera and a single lens reflex camera, using a Leica sized (35 mm) silver-halide film for example, is that the image pickup surface of the image pickup device is considerably smaller than a picture surface of the silver-halide film camera.
In a camera using a small image pickup device, since an image is formed on the small image pickup surface, the photographic optical system can be made accordingly small. However, in a digital single lens reflex camera, if the photographic optical system is considerably smaller, it is difficult to construct the finder optical system. Namely, if the light transmitted through the photographic optical system is merely split to make it incident on the finder optical system, where a primary imaging plane is formed at a position (focusing plate) optically equivalent to the image pickup device, the size of the primary imaging plane is identical to the size of the image pickup surface of the image pickup device. However, it is difficult to view the image of the small primary imaging plane as an orthoscopic erect image through a finder optical system of a conventional single lens reflex camera. To solve this problem, it is necessary to provide a relay optical system which enlarges the image of the primary imaging plane and forms an image on a second imaging plane. However, the relay optical system must be provided with a plurality of lens elements, in order to achieve a high quality image.
However, in a finder optical system of a conventional single lens reflex camera, the reflection direction of the object-carrying light reflected by the reflector located in the photographic light path is determined so that the object-carrying light is oriented substantially toward an eyepiece optical system of the finder optical system. Namely, the finder light path between the reflector and the eyepiece optical system is set to a minimum. Consequently, it is difficult to provide a large space for accommodating the relay optical system. In other words, the camera size is increased to accommodate the relay optical system.
Moreover, since a conventional digital single lens reflex camera has basically the same structure as a conventional silver halide film type camera, the structure is complex due to the assembling operation being similar to that of a silver halide film type camera. However, neither a mechanical shutter nor a film feed mechanism are necessary in a digital single lens reflex camera. Furthermore, if the mirror in the photographic light path is made of a semitransparent member, a mirror drive mechanism is not necessary, simplifying the structure of a digital single lens reflex camera.
A first object of the present invention is to provide a digital single lens reflex camera having a reflector located in the photographic light path, to facilitate the arrangement of a relay optical system which is adapted to relay an image on a focusing plate to an eyepiece optical system.
A second object of the present invention is to provide a simple digital single lens reflex camera having no movable members, which can be easily assembled.
To achieve the objects mentioned above and according to an aspect of the present invention, a digital single lens reflex camera includes a reflector located in a photographic light path to reflect object-carrying light transmitted through a photographic optical system toward a finder optical system, where an image pickup device is located at the imaging plane of the photographic optical system. The object-carrying light in the photographic light path is reflected by the reflector in a direction substantially away from an eyepiece optical system of the finder optical system. A reflection light path is formed in the vicinity of the photographic optical system and is provided with a plurality of reflection surfaces to make the light reflected by the reflector in the photographic light path incident upon the eyepiece optical system. Furthermore, a relay optical system is disposed in the reflection light path to relay an image formed on a primary imaging plane, which is optically equivalent to an image pickup surface of the image pickup device, to the eyepiece optical system.
Preferably, the relay optical system constitutes an image magnifying optical system which enlarges and re-forms the image formed on the primary imaging plane which is optically equivalent to the image pickup surface of the image pickup device.
Preferably, the reflector includes a beam splitter which partly reflects object-carrying light transmitted through the photographic optical system toward the finder optical system and transmits the remainder of the object-carrying light toward the image pickup device.
According to another aspect of the present invention, a digital single lens reflex camera is provided. The camera includes a photographic optical system; a finder optical system having an eyepiece optical system; and a reflector provided in a photographic light path to reflect object-carrying light transmitted through the photographic optical system toward the finder optical system. The reflector is arranged to reflect the object-carrying light in a direction substantially opposite to a direction of the position of the eyepiece optical system with respect to an optical axis of the photographic optical system. An image pickup device is located at an imaging plane of the photographic optical system and a reflection light path is provided with a plurality of reflection surfaces. The reflection light path being formed in the vicinity of the photographic optical system makes the light reflected by the reflector in the photographic light path incident on the eyepiece optical system. A relay optical system that is disposed in the reflection light path relays an image formed on a primary imaging plane, which is optically equivalent to an image pickup surface of the image pickup device, to the eyepiece optical system.
According to another aspect of the present invention, a digital single lens reflex camera is provided having a semitransparent member which reflects a portion of object-carrying light transmitted through a photographic optical system and permits the remainder of the object-carrying light to pass therethrough toward an image pickup device. At least one rigid substrate lies in a plane substantially perpendicular to the optical axis of the photographic optical system. At least the image pickup device is mounted thereon, and an eyepiece optical system with the optical axis thereof being substantially parallel with the optical axis of the photographic optical system. The eyepiece optical system is provided on one side of at least one rigid substrate. The semitransparent member partly reflects the object-carrying light transmitted through the photographic optical system in a direction substantially away from the eyepiece optical system. A plurality of reflection surfaces reflect the light reflected by the semitransparent member toward the eyepiece optical system. A relay optical system is disposed in a reflection light path between the semitransparent member and the eyepiece optical system to relay an image, formed on a primary imaging plane which is optically equivalent to an image pickup surface of the image pickup device, to an eyepiece optical system; are integrally formed as a finder block. The finder block is provided on the surface of the rigid substrate which is adjacent to the photographic optical system.
Preferably, the rigid substrate is provided with a first substrate on which the image pickup device is mounted and at least another substrate superimposed thereon.
Preferably, the relay optical system constitutes an image magnifying optical system which enlarges and re-forms the image formed on the primary imaging plane which is optically equivalent to the image pickup surface of the image pickup device.
Preferably, the finder block is integrally provided with the eyepiece optical system of the finder optical system and is provided in the upper portion of the rigid substrate.
According to another aspect of the present invention, a digital single lens reflex camera is provided including a photographic optical system, a finder optical system having an eyepiece optical system and an image pickup device located at an imaging plane of the photographic optical system. A semitransparent member which reflects a portion of object-carrying light transmitted through the photographic optical system and permits the remainder of the object-carrying light to pass therethrough toward the image pickup device. The semitransparent member is arranged to reflect the object-carrying light in a substantially opposite direction with respect to the position of the eyepiece optical system and with respect to the optical axis of the photographic optical system. A reflection light path is provided with a plurality of reflection surfaces, the reflection light path being formed in the vicinity of the photographic optical system to make the light reflected by the reflector in the photographic light path incident on the eyepiece optical system. A relay optical system that is disposed in the reflection light path to relay an image formed on a primary imaging plane that is optically equivalent to an image pickup surface of the image pickup device to the eyepiece optical system. At least one rigid substrate on which at least the image pickup device is mounted, with the rigid plate lying in a plane substantially perpendicular to the optical axis of the photographic optical system. A finder block that integrally forms the semitransparent member, a plurality of the reflection surfaces and the relay optical system. The finder block being disposed on the surface of the rigid substrate located adjacent to the photographic optical system.
Preferably, the eyepiece optical system is arranged so that an optical axis thereof is substantially parallel with the optical axis of the photographic optical system and is provided on one side of the rigid substrate.
Preferably, the plurality of reflection surfaces, described in each above-mentioned aspect of the present invention, includes at least one of a penta prism, a penta roof-prism, and a mirror.
The present disclosure relates to subject matter contained in Japanese Patent Application No. 10-323213 (filed on Nov. 13, 1998) and Japanese Patent Application No. 10-323214 (filed on Nov. 13, 1998) which are expressly incorporated herein by reference in their entireties.